Air New Zealand is broadening its commercial links with American carrier United Airlines.
The airlines will share revenue on all services between New Zealand and the United States from the middle of the year, and will also promote and sell each other's services, including their domestic networks.
The two are members of the global Star Alliance and already have code sharing and support each other with ground services.
The agreement will come into effect on July 1 when United Airlines starts flying between San Francisco and Auckland.
Air New Zealand's chief executive Christopher Luxon said the alliance should help boost tourism from the US, already the third-highest source of visitors.
"To have a strong home market carrier like United Airlines working with us to grow this market through its extensive sales and distribution channels in the US will provide a significant boost to inbound tourism."
The agreement came as United's competitor American Airlines prepared to resume flights from the United States to New Zealand in conjunction with Australia's Qantas.